Endoscopic microsurgical instruments and methods

ABSTRACT

The invention provides devices and method for performing extremely small-scale, minimally-invasive microsurgery such as thoracoscopic coronary artery bypass grafting. The instruments of the invention utilize a symmetrical, forcep-like actuator which provides extremely precise actuation and control of the instrument and which mimics the feel of instruments used in conventional open surgical procedures. The instruments generally include a pair of coaxially arranged shafts, an end-effect at the distal ends of the shafts, and an actuator at the proximal ends of the shafts. The actuator includes a pair of arms pivotally coupled to one of either the outer or inner shaft, and a pair of links pivotally coupled at one end to the arms, and at a second end to the other of the shafts. The links are coupled to a proximal portion of the arms to maximize mechanical advantage and reduce interference. The actuator may be easily adapted for either pull-type or push-type actuation, and for either outer shaft or inner shaft translation. The end-effectors may have a variety of configurations, including needle drivers, forceps, scissors, and clip appliers.

This is a Continuation of application Ser. No. 08/560,441 filed Nov. 17,1995, now U.S. Pat. No. 5,618,306 which is a division of Ser. No.08/194,946, filed Feb. 14, 1994, now U.S. Pat. No. 5,501,698.

FIELD OF THE INVENTION

This invention relates generally to instruments for performingminimally-invasive surgery, and more specifically, to instruments forperforming extremely small-scale, minimally-invasive microsurgeries suchas coronary artery bypass grafting.

BACKGROUND OF THE INVENTION

Minimally-invasive surgical techniques, such as thoracoscopy,laparoscopy, pelviscopy, endoscopy, and arthroscopy, minimize patienttrauma by providing access to interior body cavities through very smallincisions or through percutaneous cannulas known as trocar sleeves. Toperform a surgical procedure, elongated, low-profile instruments areintroduced into a body cavity through these incisions or trocar sleeves.Visualization is facilitated by percutaneous visualization devices knownas laparoscopes, endoscopes, arthroscopes, and the like, which typicallyconsist of a video camera configured for introduction through a smallincision or trocar sleeve to allow observation of the body cavity on avideo monitor. By obviating the need for a large, open incision toexpose the body cavity, minimally-invasive techniques can significantlyreduce the pain, recovery period, morbidity and mortality rates, andcost of open surgical procedures without a sacrifice in efficacy.

In recent years, minimally-invasive techniques have been developed tofacilitate the performance of a variety of surgical procedures on organsand ducts of the abdominal and pelvic cavities. Well-known examples ofsuch procedures include laparoscopic cholecystectomy, laparoscopicappendectomy, laparoscopic hysterectomy, and laparoscopic hernia repair.

A particularly important milestone in minimally-invasive surgery hasbeen attained with the development of thoracoscopic techniques forsurgery of the heart and great vessels. Such techniques arc described inco-pending, commonly-assigned U.S. patent application Ser. No.08/023,778, filed Feb. 22, 1993, now U.S. Pat. No. 5,452,733, thecomplete disclosure of which is hereby incorporated herein by reference.In that application, thoracoscopic techniques for performing coronaryartery bypass grafting (CABG) are described which eliminate the need forthe sternotomy or other form of gross thoracotomy required byconventional, open surgical techniques. In thoracoscopic CABG, anarterial blood source such as the internal mammary artery (IMA) isdissected from its native location, transected, and prepared forattachment to an anastomosis site on a target coronary artery, commonlythe left anterior descending coronary artery (LAD). A portion of thetarget coronary artery containing the anastomosis site is then dissectedaway from the epicardium, and a small incision is made in the arterialwall. The distal end of the arterial blood source (e.g. IMA) is thenanastomosed over the incision in the target coronary artery, usually bysuturing. Each of these steps is performed by means of instrumentsintroduced through small incisions or trocar sleeves positioned withinintercostal spaces of the rib cage, under visualization by means of anendoscope or other percutaneous visualization device.

Because the CABG procedure requires complex microsurgery to be carriedout on extremely small body structures, surgical instruments designedfor laparoscopic and other minimally-invasive applications are notgenerally suitable for performing thoracoscopic CABG. Most laparoscopicprocedures, for example, target body structures which are quite large incomparison to the coronary vessels, and do not require the high degreeof precision required by microsurgeries such as CABG. Accordingly,laparoscopic instruments generally have relatively large end-effectorswith relatively large ranges of movement, making such instrumentsill-suited for use on very small structures like the coronary vessels.In addition, such instruments commonly have finger loops or pistol-typeactuators gripped in the user's palm or between the user's thumb andforefinger, limiting the sensitivity and precision with which suchinstruments can be manipulated and actuated. Such finger loops orpistol-type grips also are limited to a single orientation in the user'shand and cannot be repositioned in the hand to allow better access to abody structure or to change the orientation of the end-effector.

The advent of thoracoscopic CABG and other minimally-invasivemicrosurgical procedures therefore demands a new generation ofmicrosurgical instruments specifically designed to meet the unique needsof such procedures. These instruments must have a small profile forintroduction through small incisions or trocar sleeves, and a lengthsufficient to reach the heart and other thoracic organs and vessels fromvarious percutaneous access points. The instruments must haveend-effectors adapted to perform delicate, high-precision microsurgeryon very small vessels, including end-effectors having very smalldimensions and very short ranges of motion. The instruments must haveactuators that facilitate ergonomic, one-handed actuation withsensitivity and precision, preferably having a stroke which is largeenough for comfortable actuation by the fingers and which is reduced toa very short range of motion at the end-effector. Desirably, theactuators will have a configuration which is analogous to surgicalforceps or to other types of microsurgical instruments commonly utilizedin open surgical procedures, shortening the learning curve required foradoption of minimally-invasive microsurgical techniques.

SUMMARY OF THE INVENTION

This invention provides instruments and methods to facilitate theperformance of minimally-invasive microsurgical procedures, andparticularly, the performance of thoracoscopic CABG and other procedureson the heart and great vessels. The instruments of the inventionfacilitate a variety of surgical activities, including application ofclips or staples, suturing, incision, transection, dissection,retraction, and manipulation, and are specially adapted for use onextremely small body structures such as the coronary blood vessels. Toallow precise microsurgery to be performed on a very small scale, theinstruments are adapted to he held in a single hand in a manneranalogous to surgical forceps. The instruments are actuated by a pair ofsymmetrical, proximally-hinged, forcep-like arms which can be pivoted bythe fingers for sensitive and precise actuation of an end-effector. Thesymmetry of actuation allows each instrument to be rotated or otherwiserepositioned within the user's hand to change the orientation of theend-effector without compromising the ease of actuation. Moreover, theactuator's proximal hinge, along with a proximally-disposed linkagemechanism, allow the distance between the user's hand and the bodysurface to be minimized for optimal control of the instrument.

In a preferred embodiment, a microsurgical instrument according to theinvention comprises an outer shaft having an axial lumen, and an innershaft slidably disposed in the axial lumen. An end-effector is coupledto the distal end of the inner shaft and is movable relative to theouter shaft. An actuator is disposed at the proximal end of the outershaft for actuating the end-effector. The actuator includes first andsecond arms each coupled at its proximal end to one of either the outershaft or the inner shaft, each arm extending distally and biasedoutwardly so as to form an acute angle with the outer shaft. A link iscoupled to each arm and to the shaft to which the arms themselves arenot coupled. In this way, the first and second arms are symmetricallypivotable so as to pivot the links, thereby translating the inner shaftrelative to the outer shaft to actuate the end-effector.

The end-effector of the instrument may have a variety of configurationsfor performing a variety of functions. The end-effector may comprise apair of jaws which may be adapted for various purposes, includingcutting, grasping, holding a suture needle, and applying a clip orstaple. In an exemplary embodiment, the end-effector comprises a firstjaw fixed to the outer shaft, and a second jaw coupled to the innershaft, such that translating the inner shaft relative to the outer shaftmoves the second jaw relative to the first jaw. The second jaw may bepivotable, axially slidable, rotatable, or deflectable relative to thefirst jaw. The jaws may be configured to have opposing gripping surfacesfor grasping tissue or holding a suture needle, or may have sharpcutting edges movable in a shearing relationship relative to each otherfor cutting tissue. The jaws may further be disposed at various anglesand orientations relative to the inner and outer shafts to provide arange of end-effector configurations to meet a variety of surgicalneeds.

Alternatively, the end-effector may be adapted for applying a clip orstaple to a body structure. In an exemplary configuration, theend-effector includes a pair of jaws fixed to tile distal end of theinner shaft and adapted to hold a clip or staple between them. The jawsare biased away from each other and are deflectable toward one another.Upon actuation, the outer shaft is configured to slide distally over aproximal portion of the jaws so as to urge the jaws toward one another,thereby closing the clip or staple.

Preferably, the instruments of the invention arc adapted for extremelysmall scale microsurgical procedures such as coronary anastomosis. Tofacilitate such procedures, the arms of the actuator are configured toprovide a comfortable range of motion for forcep-like finger actuation,a range of motion which is reduced to a very small range of motion atthe end-effector, thereby providing sensitive and precise actuation forvery small end-effector movements.

In actuating very small end-effectors through very small ranges ofmotion, the minimization of friction is important in providing smoothand precise actuation. To reduce friction, the links are coupled to theshaft (either inner or outer) such that the transverse force exerted onthe shaft by one link is opposed by a transverse force exerted on theshaft by the other link. Usually, this is accomplished by coupling theinner ends of the links to the shaft at points which are equidistantfrom the proximal end of the shalt. In this way, as the arms are pivotedinwardly, the links do not urge the inner shaft against the outer shaft(or vice versa), which would produce friction as the shafts moverelative to each other.

The arms may be bendable or rigid, and the arms may be coupled to theinner or outer shaft in various ways, including by pins, by livinghinges, by bar linkages, or by other means. Preferably, however, thearms arc hinged at their proximal ends to the inner or outer shaft. Ameans for biasing the arms outward is provided, which in one embodimentcomprises a flat spring coupled to each arm. With a hinge arrangement,the arms may be rigid, rather than being bendable or resilient,permitting a wide variety of materials, and geometries to be used. Inthis way, the arms may be designed for optimum performance and minimumcost.

The links may be configured so as to translate the inner shaft eitherdistally or proximally relative to the outer shaft as the arms arepivoted inwardly. To provide translation of the inner shaft proximally,the inner ends of the links are disposed proximal to the outer ends ofthe links. To provide translation of the inner shaft distally, the innerends of the links are disposed distal to the outer ends of the links.

The instruments of the invention are further advantageous in that theyallow the user to hold and actuate the instrument from a position whichis as close as possible to the surface of the patient's body, optimizingcontrol of the instrument. The proximally-hinged arms permit the user toengage the arms near their distal ends, and to introduce the instrumentinto the patient's body cavity through an incision or trocar sleeve upto the distal ends of the arms. In this way, the user may engage andmanipulate the instrument in a position immediately adjacent the surfaceof the patient's body. The links are preferably coupled to the arms in aproximal portion thereof so as not to interfere with or limitintroduction of the instrument. Proximal disposition of the links alsomaximizes the mechanical advantage obtained from the forces exerted onthe distal ends of the arms, and allows the stroke of the arms to beamplified relative to the range of motion of the end-effector.

The invention may further include means for locking the arms in a closedposition. This may be useful to ensure the jaws of the end-effector areclosed for introduction or removal from the body cavity, or to reducethe risk of inadvertent injury to the patient caused by an openend-effector.

Usually, the instruments of the invention are adapted for endoscopicuses, wherein the end-effector is introduced though a small incision ortrocar sleeve into the body cavity. To facilitate such introduction, theprofile of the end-effector and outer shaft are preferably minimized. Inone embodiment, the outer shaft has a diameter of less than about 5 mm.

The instruments of the invention may be utilized to perform a variety ofsurgical procedures, both conventional, open) procedures andminimally-invasive procedures. In an endoscopic method of treatmentaccording to the invention, the distal end of the instrument isintroduced through a percutaneous penetration into a body cavity, and,under visualization by means of a scope introduced through apercutaneous penetration, a distal portion of at least one arm ispressed inwardly to symmetrically pivot both arms toward the shaft,thereby closing the jaws of the end-effector on a body structure in thebody cavity. In various embodiments, the method may be used for cutting,dissecting, transecting, retracting, or otherwise manipulating a bodystructure, as well as for suturing, or for applying clips or staples toa body structure. In a particularly preferred embodiment, the method isutilized in a thoracoscopic CABG procedure for dissecting a graft vesselsuch as the IMA from its native location, and performing an anastomosisof the graft vessel to a coronary artery such as the LAD.

A further understanding of the nature and advantages of the inventionmay be realized by reference to the remaining portions of thespecification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-1B are side and top elevational views, respectively, of amicrosurgical instrument constructed in accordance with the principlesof the invention.

FIG. 1C is an illustration of a patient's chest in partial sectionillustrating the use of the instrument of FIGS. 1A-1B through a trocarsleeve.

FIGS. 2A-2B are side and top cross-sectional views, respectively, of afirst embodiment of an actuator in the microsurgical instrument of FIG.1.

FIG. 2C is a side cross-sectional view of the actuator of FIG. 2A in aclosed position.

FIGS. 3A-3B are side and top cross-sectional views, respectively, of asecond embodiment of an actuator in the microsurgical instrument ofFIG. 1. FIG. 3C is a side cross-sectional view of the actuator of FIG.3A in a closed position.

FIGS. 4A-4B are side partial cross-sectional views of an actuator in themicrosurgical instrument of FIG. 1 showing two alternative embodimentsof an actuator locking mechanism.

FIGS. 5-6 are side, partial cross-sectional views of two alternativeembodiments of an end-effector in the microsurgical instrument of FIG.1.

FIG. 7A is a side partial cross-section of an alternative embodiment ofan end-effector in the microsurgical instrument of FIG. 1.

FIGS. 7B-10 are side elevational views of various embodiments of anend-effector in the microsurgical instrument of FIG. 1.

FIG. 11 is a side, partial cross-sectional view of a further embodimentof a microsurgical instrument constructed in accordance with theprinciples of the invention.

FIG. 12 is a side elevational view of a distal portion of themicrosurgical instrument of FIG. 11 illustrating the application of asurgical clip to a vessel.

FIG. 13 is a transverse cross-section taken through a patient's thoraxinferior to the heart showing the positioning of trocar sleeves andmicrosurgical instruments according to the method of the invention.

FIGS. 14-15 and 17 are anterior elevational views of a patient's heart,illustrating the performance of a coronary artery anastomosis accordingto the method of the invention.

FIGS. 16A-16E illustrate a method of suturing a graft vessel to acoronary artery according to the method of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The instruments and methods of the invention facilitate the performanceof microsurgical procedures with high precision and control. Theinvention is therefore useful in any procedure where very small bodystructures are involved or where highly-precise, very small-scalesurgical maneuvers are being performed, whether conventional, openprocedures or minimally-invasive procedures. Because, the instrumentsand methods are well-adapted for the performance of surgery throughsmall, percutaneous incisions or trocar sleeves, the invention isparticularly well-suited for the performance of minimally-invasiveprocedures such as thoracoscopy, laparoscopy, and pelviscopy. In aparticularly preferred embodiment, for example, the instruments andmethods of the invention are utilized for the performance ofthoracoscopic CABG procedures, wherein specialized instruments arcintroduced through percutaneous penetrations and/or trocar sleeves todissect a graft vessel such as the IMA from its native location, incisea coronary artery such as the LAD downstream of an arterial lesion, andanastomose the graft vessel to the coronary artery. No knownthoracoscopic, laparoscopic, or other minimally-invasive surgicalinstruments are suitable for performing the ultra-precise microsurgeryrequired in a thoracoscopic CABG procedure.

A first preferred embodiment of a microsurgical instrument according tothe invention is illustrated in FIGS. 1A-1C. Microsurgical instrument 20includes an outer shaft 22 having a proximal end 24 and a distal end 26.Proximal end 24 of outer shaft 22 is mounted to an actuator 28. Actuator28 includes a body 30 having a distal end 32 to which outer shaft 22 ismounted, and a proximal end 34 to which a pair of arms 36 are pivotallycoupled. Arms 36 each have a proximal end 35 coupled to body 30, and adistal end 37 which is biased outwardly from outer shaft 22 to form anacute angle therewith. A finger grip 38 is disposed near the distal end37 of each arm 36, the finger grips comprising a plurality of grooves orother textural features to facilitate gripping and actuating theinstrument.

As shown in FIG. 1C, actuator 28 is configured to be held between thethumb T and index finger F of the user's hand, similar to the manner inwhich conventional forceps are held. Arms 36 may be engaged on fingergrips 38 by the tips of finger F and thumb T, with the proximal ends 35of arms 36 resting on the user's hand between and/or behind index fingerF and thumb T. Held in this way, instrument 20 is positionable with highprecision and control, and may be actuated with great ease by exertinginward pressure on finger grips 38. In an exemplary embodiment, arms 36are 8 to 12 cm. in length, and form an angle αbetween 3° and 30°,preferably between 5° and 10°, with outer 22 in the open position.

Returning to FIGS. 1A-1B, an end-effector 40 is mounted to the distalend of outer shaft 22. End-effector 40 may have various configurationsaccording to the function which instrument 20 is adapted to perform. Inthe embodiment illustrated, end-effector 40 is adapted for holding asuture needle, and includes a fixed jaw 42 mounted to outer shaft 22,and a movable jaw 44 pivotally mounted to outer shaft 22 and coupled toactuator 28 by means of an inner shaft 46, described more fully below.By pivoting arms 36 inward toward outer shaft 22, movable jaw 44 may bepivoted toward fixed jaw 42 in order to clamp a suture needle Ntherebetween as in FIG. 1C.

Outer shaft 22 and end-effector 40 are preferably configured forendoscopic uses, and have a profile suitable for introduction through asmall percutaneous incision or trocar sleeve TS into a body cavity BC,as illustrated in FIG. 1C. Ideally, the profile (cross-sectional area)of outer shaft 22 is minimized to provide maximum clearance through anincision or trocar sleeve, thereby maximizing the maneuverability of theinstrument. However, for most procedures, outer shaft 22 must havesignificant rigidity to resist bending or buckling. For endoscopicapplications, outer shaft 22 must also have a length sufficient to reacha target site within a body cavity from a position outside of the body.In an exemplary embodiment suitable for thoracoscopic surgery on theheart, outer shaft 22 is constructed of a metal such as aluminum,titanium or stainless steel, has a round cross-section with a diameterof 2 to 10 mm, preferably about 3 to 5 mm, and has a length of about 10to 30 cm., preferably about 20 to 25 cm.

The instruments of the invention may be configured for either pull-typeor push-type actuation of end-effector 40. An exemplary embodiment of apull-type actuator 28 is illustrated in FIGS. 2A-2C. Outer shaft 22 isfixed to a sleeve 45 retained within an axial bore 47 in body 30. Asetscrew 49 engages sleeve 45 and permits axial adjustment of outershaft 22 relative to body 30. Arms 36 are hinged to body 30 by pins 48.Means are provided for biasing arms 36 outwardly, which may comprise aflat spring 50 at the proximal end 34 of body 30 shaped so that each endof spring 50 is disposed between an arm 36 and body 30. Flat spring 50may be a resilient, flexible metal such as stainless steel.

Various alternative means may be used for coupling arms 36 to body 30,such as a living hinge or bar linkage. Alternatively, arms 36 may befixed to body 30 and/or to each other, and provided with sufficientflexibility to allow distal ends 37 to be deflected toward outer shaft22. The hinge pin arrangement illustrated provides a simple anddependable coupling with the advantage that arms 36 need not beflexible, allowing a wide variety of rigid materials to be used for thearms, including metals and plastics.

A pair of links 52 each have an outer end 54 pinned to an arm 36 and aninner end 56 pinned to a cylindrical clevis 58. Outer ends 54 arecoupled to arm 36 by pins 55 and bushings 57. Body 30 has an aperture 60in which inner ends 56 of links 52 are attached to proximal end 62 ofclevis 58. Proximal end 62 of clevis 58 is bifurcated by a channel 64 inwhich inner ends 56 of links 52 are coupled by a pin 65. Clevis 58 isslidable within axial bore 47 in body 30. A threaded hole 68 extendsaxially through a distal portion of clevis 58. A screw 70 is fixed to aproximal end 72 of inner shaft 46 and is threaded into hole 68, suchthat inner shaft 46 moves in tandem with clevis 58.

In operation, when arms 36 are pivoted toward outer shaft 22, links 52pull clevis 58 and inner shaft 46 proximally relative to outer shaft 22,to the position shown in FIG. 2C. Releasing inward force on arms 36allows them to return to their outward position under the force ofspring 50. The outward travel of arms 36 is limited by the engagement ofscrew 70 and/or clevis 58 against the proximal end of sleeve 45. Theextent of outward travel of arms 36, and hence the axial translation ofinner shaft 46, may be adjusted by loosening setscrew 49 and axiallyrepositioning sleeve 45.

Outer ends 54 of links 52 may be coupled to arms 36 at various positionsbetween their proximal ends 35 and distal ends 37. In a preferredembodiment, however, outer ends 54 are coupled to arms 36 in a proximalportion thereof, preferably at a point more than ball the length of arm36 from its distal end 37 or from finger grip 38. By maximizing thedistance between the point at which the user presses on arms 36 and thepoint of coupling to links 52, mechanical advantage is maximized. At thesame time, this proximal positioning of the links leaves open themajority of the area between the distal portion of arms 36 and outershalt 22, eliminating any possibility of interference between links 52and the patient's body, trocar sleeves, the user, or other objects. Thisis particularly useful when the instruments are introduced into thepatient's body through small incisions or trocar sleeves inlaparoscopic, thoracoscopic, or other minimally-invasive surgicalprocedures. As shown in FIG. 1C, the instruments of the invention may beintroduced through such small access ports into the body cavity to themaximum extent (up to distal ends 37 of arms 36), such that the distancebetween the user's hand U and the patient's body P is minimized. Suchpositioning facilitates maximum control of the instrument forultra-precise manipulation.

FIGS. 3A-3C illustrate a push-type embodiment of actuator 28 in whichinner shaft 46 is configured to be translated distally rather thanproximally relative to outer shaft 22 when arms 36 are pivoted inward.The embodiment of FIGS. 3A-3C is in many respects similar to that ofFIGS. 2A-2C, except that inner ends 56 of links 52, coupled to proximalend 62 of clevis 58, are disposed distal to outer ends 54, coupled toarms 36. In this way, when arms 36 are pivoted inward, links 52 pushclevis 58 and inner shaft 46 distally. To limit the outward travel ofarms 36, as well as the proximal movement of inner shaft 46, a limitscrew 74 is disposed in a threaded hole 76 in a proximal end of body 30.Links 52 each have an extension 78 on a proximal side thereof configuredto engage a distal end 80 of limit screw 74 when arms 36 are in anoutward position. The degree of outward travel of arms 36, as well asthe axial translation of inner shaft 46, may be adjusted by changing thedepth of limit screw 74 within hole 76.

Referring now to FIGS. 4A-4B, actuator 28 may further include lockingmeans 86 for maintaining arms 36 in an inward position when pressure isreleased therefrom. Locking means 86 may have various configurations,including the single-position design of FIG. 4A, and the ratcheteddesign of FIG. 4B. In the embodiment of FIG. 4A, locking means 86comprises a catch 88 attached to each of arms 36 near the distal end 37thereof. At least a first catch 88A is attached to arm 36 by aresilient, deflectable beam 90, allowing catch 88A to deflect laterallyupon engagement with second catch 88B when arms 36 are pressed towardone another. Catch 88A has a stepped portion 91 which is deflected uponcontact with the tapered back side of end portion 92. After clearing endportion 92, stepped portion 91 partially recoils from the deflection andresides beneath end portion 92, preventing arms 36 from returning totheir outward positions. To release arms 36, they are pressed furtherinward, whereby catch 88A completely clears end portion 92 of catch 88Band returns to its undetected position. As arms 36 return to theiroutward positions, the back side of catch 88A slides along the taperedfront side of end portion 92.

In the embodiment of FIG. 4B, locking means 86 comprises a ratchetingmechanism to allow arms 36 to be maintained in any of a number ofpositions between fully open and fully closed. In this embodiment, arocker arm 94 is pivotally coupled to arm 36A near a distal end 37thereof. A first end 96 of rocker arm 94 extends through a slot 98 inarm 36, and has a finger pad 100 with grooves or other textural featuresto reduce slippage when engaged by the user. A plurality of teeth 102are disposed on a lateral side of rocker aim 94, and are configured toengage a pawl 104 on second arm 36B. A second end 105 of rocker arm 94extends through a slot 106 in second arm 36B. A biasing means such as aleaf spring 108 is coupled to rocker arm 94 and to arm 36A to urge teeth102 against pawl 104. In this way, as arms 36 are pressed inward, rockerarm 94 extends through slot 106 and teeth 102 ride sequentially alongpawl 104. When arms 36 are in a desired position, pressure may bereleased and the engagement of pawl 104 against teeth 102 prevents arms36 from returning outwardly. When arms 36 are to be released, finger pad100 is pushed distally, pivoting rocker aim 94 in a clockwise direction,and disengaging teeth 102 from pawl 104.

The microsurgical instruments of the invention may have a number ofdifferent end-effectors suitable for performing a variety of surgicalactivities. Several examples of such end-effectors are illustrated inFIGS. 5-10. It will be understood to those of ordinary skill in the artthat the principles of the invention may be applied to variousend-effector configurations in addition to those illustrated anddescribed specifically here.

The end-effectors in the microsurgical instruments of the invention maybe configured for either pull-type or push-type actuation, dependingupon whether the pull-type actuator of FIGS. 2A-2C or the push-typeactuator of FIGS. 3A-3C is used. An exemplary embodiment of a pull-typeend-effector is illustrated in FIG. 5. End-effector 40 comprises a fixedjaw 112 attached to distal end 26 of outer shaft 22, and a movable jaw114 pivotally coupled to outer shaft 22 or to fixed jaw 112 at a pivotpoint 115. Inner shaft 46 has a distal end 116 pivotally coupled to arearward portion 118 of movable jaw 114 proximal to pivot point 115. Itis evident that, as inner shaft 46 is translated proximally relative toouter shaft 22, movable jaw 114 pivots toward fixed jaw 112.

An exemplary embodiment of a push-type end-effector is illustrated inFIG. 6. In this embodiment, pivot point 115 is located near a proximalend of movable jaw 114, and inner shaft 46 is coupled to movable jaw 114distal to pivot point 115. It may be seen that translation of innershaft 46 distally relative to outer shaft 22 will pivot movable jaw 114toward fixed jaw 112.

The choice to use either a pull-type end-effector or a push-typeend-effector is guided by a variety of considerations, including thegeometry of the end-effector, the function which the end-effector isdesigned to perform, and the preference of the user for either push-typeor pull-type actuation. For example, where high forces are needed in theend-effector to perform functions such as gripping or cutting, pull-typeactuation is often preferred to eliminate the possibility of buckling ininner shaft 46. In some end-effectors designed for punching or shearing,push-type actuation is often preferred to provide tight, sliding contactbetween the jaws. In addition, the user may prefer the jaws of theend-effector to be normally closed when arms 36 of actuator 28 are in anoutward position, such that the jaws are opened by pressing arms 36inwardly. In such cases, the instruments of the invention may be easilyadapted for either pull-type or push-type actuation by providing thepull to close end-effector of FIG. 5 with the push to close actuator ofFIG. 3, or by providing the push to close end-effector of FIG. 6 withthe pull to close actuator of FIG. 2.

FIGS. 7-10 illustrate exemplary end-effector configurations suitable forperforming various surgical functions. FIGS. 7A-7B illustrate twoembodiments of grasping forceps. Both embodiments are useful for avariety of purposes, however, the embodiment of FIG. 7A is particularlyuseful in mobilizing the internal mammary artery (IMA) for grafting to acoronary artery, as described below. Both embodiments include a fixedjaw 112 and movable jaw 114 have gripping surfaces 120, 122 disposed inopposition to each other so as to come into contact upon closing thejaws. Gripping surfaces 12(0, 122 have textural features such astransverse grooves or teeth 124 to improve grip on tissue or otherobjects. Various well-known jaw designs may be used, such as DeBakey,Cooley, Mayo, or Babcock. Jaws 112, 114 may be of various sizes andshapes depending upon the particular procedures for which they areadapted. In a particularly preferred embodiment, jaws 112, 114 areadapted for very precise work on extremely small body structures inmicrosurgeries such as CABG, having a length usually between 3 and 15mm, preferably between 5 and 10 mm. In the embodiment of FIG. 7A, jaws112, 114 are disposed at an angle, preferably between about 45° and 90°,relative to the distal direction defined by outer shaft 22, tofacilitate grasping the IMA when mobilizing it from the chest wall. Inthe embodiment of FIG. 7B, jaws 112 are generally orthogonal with outershaft 22 and are tapered in the distal direction to provide a distalportion of reduced size for enhanced access into small spaces and foruse on extremely small structures.

FIG. 8 illustrates a forward-cutting scissors embodiment of end-effector40. In this embodiment, fixed jaw 112 and movable jaw 114 each have asharpened cutting edge 126 along an inner side thereof. Movable jaw 114is configured to pivot alongside fixed jaw 112 such that cutting edges126 slide along one another in a shearing action. Usually, jaws 112, 114are tapered to a sharp distal point 128. Preferably, in the scissorembodiment, jaws 112, 114 are again adapted for use in CABG and othermicrosurgeries, laving a length in the range of 3 to 10 mm, andpreferably 3 to 5 mm. Jaws 112, 114 may be disposed at a variety ofdifferent angles relative to the distal direction defined by outer shaft22, from +90° to -90°, depending upon the particular cutting task to beperformed.

FIG. 9 illustrates a rearward-cutting scissors embodiment ofend-effector 40. In this embodiment, jaws 112, 114 are much like thosein the forward-cutting scissors embodiment of FIG. 8, having a sharpenedcutting edge 126 and tapering to a distal point 128. However, tofacilitate cutting in a proximal direction (toward the user), jaws 112,114 are disposed at an angle between 90° and 270° relative to the distaldirection as defined by outer shaft 22, such that distal points 128point generally rearward.

FIG. 10 illustrates a suture needle holder embodiment of end-effector40. In this embodiment, jaws 112, 114 have contact faces 130, 132disposed in opposition to each other and which engage each other uponclosure. Contact faces 130, 132 are adapted for gripping a suture needletightly between jaws 112, 114 and manipulating the needle for purposesof applying a suture to a body structure. Because such suture needlesare typically steel or other hard metal, it is usually desirable toprovide an insert 134 of hardened steel, carbide, or other metal on eachjaw to enhance grip on the needle and to reduce wear on the grippingsurfaces. Contact faces 130, 132 are preferably provided with grooves,diamond knurl patterns, or other textural features to improve grip. In apreferred embodiment, jaws 112, 114 are adapted for holding a BV-1 typesuture needle suitable for coronary anastomosis and other microsurgicalapplications, the jaws usually having a length between 3 and 10 mm, andpreferably between 3 and 5 mm. Jaws 112, 114 may also be curved about atransverse axis to facilitate holding a suture needle at various anglesrelative to shaft 22.

In the embodiments described above, outer shaft 22 remains stationaryrelative to actuator 28 and inner shaft 46 is translated either distallyor proximally relative to outer shaft 22. It should be understood thatthe instruments of the invention may also be configured so that innershaft 46 remains stationary relative to actuator 28 and outer shaft 22is translated relative to inner shaft 46. An example of the latterconfiguration is illustrated in FIG. 11. Arms 36 are coupled to a body140, which has an axial bore 141 in which proximal end 142 of innershaft 46 is fixed. A proximal end 144 of outer shaft 22 is fixed to asleeve 146 having flats 148 on the lateral sides of a proximal endthereof. A pair of links 150 are coupled at their outer ends 152 to arms36, and at their inner ends 154 to flats 148 on sleeve 146. As describedabove, links 150 may be configured to translate outer shaft 22 eitherdistally, as illustrated, or proximally relative to inner shaft 46 bypositioning inner ends 154 either distal or proximal relative to outerends 152.

FIG. 11 further illustrates an exemplary embodiment of an end-effectorwith which an actuator configured to translate outer shaft 22 isparticularly useful. In this embodiment, end-effector 156 comprises aclip applier for applying a surgical clip 158. End-effector 156 may beadapted to apply surgical clips or staples of various types and sizes,including, for example, a Hemoclip® or Atrauclip™ brand surgical clipavailable from Pilling/Weck of Fort Washington, Pa. Such clips are atitanium or tantalum alloy or pure metal material and have a pair ofdistally-pointing legs 160 joined together at an apex 162 to form amodified "U" or "V" shape. End-effector 156 includes a pair of jaws 164adapted to receive clip 158 between them. Jaws 164 extend distally froma bifurcated shank 166 attached to distal end 168 of inner shaft 46.Shank 166 has a straight proximal portion 170 and a flared distalportion 172. As outer shaft 22 translates distally, its distal end 174engages flared portion 172 of shank 166 and urges jaws 164 toward eachother, thereby closing clip 158 held therebetween.

As illustrated in FIG. 12, clip 158 may be positioned about a bodystructure such as a severed blood vessel BV. Actuator 28 may then beactuated to close clip 158 on blood vessel BV to stop blood flowtherethrough. A plurality of clips 158 may be applied to blood vessel BVto isolate a portion of the vessel or to ensure adequate ligation. Thistechnique may be utilized during various surgical procedures includingCABG, as described more fully below.

End-effector 156 and clip 158 may have various sizes and shapes, but ina preferred embodiment, are adapted for use in performing CABG and othermicrosurgeries. In such surgeries, legs 160 of clip 158 may have alength of 2 to 5 mm, preferably 3 to 4 mm, with the distance betweenlegs 160 being 2 to 4 mm. Larger sizes of clips may be employed forlarger vessels. End-effector 156 is dimensioned accordingly.

It will be understood to those of ordinary skill in the art that anactuator configured to translate inner shaft 46 relative to a stationaryouter shaft 22 may also be adapted to actuate a clip applier like thatof FIG. 11. However, it is usually desirable to maintain a constantdistance between the user's hand and the body structure to which a clipis to be applied. Therefore, the actuator configuration illustrated inFIG. 11 is generally preferred, since end-effector 156 remainsstationary relative to actuator 28 as outer shaft 22 translates distallyto close jaws 164.

The method of the invention will now be described with reference toFIGS. 13-17. While a preferred method of performing coronary arteryanastomosis in a thoracoscopic CABG procedure will be described indetail here, it should be understood that the principles of theinvention may be applied to a wide variety of surgical procedures, bothconventional, open procedures as well as minimally-invasive procedures.

With the patient under general anesthesia, the patient's left lung L isdeflated using well-known techniques. Several small incisions are madein the left anterior chest through which trocar sleeves may bepositioned to provide access into the thoracic cavity. As illustrated inFIGS. 13, trocar sleeves 180 are positionable within the intercostalspaces I between adjacent ribs R of the rib cage, typically having anouter diameter of less than 12 mm and an inner diameter of 5 to 10 mm.Trocar sleeves 180 thus provide access ports through which theinstruments of the invention may be introduced into the thoracic cavityto perform the CABG procedure.

An endoscope 182 is then introduced into the body cavity through atrocar sleeve 180 to facilitate visualization of the thoracic cavity.Endoscope 182 may include an eyepiece 184 for direct visualization ofthe body cavity, and/or a video camera (not shown) mounted to body 185for video-based(viewing. Distal end 188 of endoscope 182 may besteerable or disposed at an angle to facilitate visualization of theheart H. Endoscope 182 may further include a connector 186 forconnecting to a light source (not shown) for transmitting light todistal end 188 for illuminating the thoracic cavity. Endoscope 182 maybe a commercially-available endoscope such as the 45° endoscope,available from Olympus, Medical Instruments Division, of Lake Success,N.Y.

The first surgical step to be performed in the CABG procedure is themobilization of a graft vessel to create a new arterial blood source.Ordinarily, such a graft will be harvested before the patient has beenplaced on cardiopulmonary bypass and the patient's heart has beenstopped. One common type of graft vessel is a vein graft harvested fromanother part of the patient's body, usually the leg. A second commontype of graft vessel is the internal mammary artery (IMA), typically theleft IMA (LIMA), in the anterior wall of the patient's chest. Prostheticgrafts may also be used. The IMA is often the preferred form of graftvessel, as it generally maintains patency for a longer period after theCABG procedure, requires less preparation for anastomosis, and isaccessible within the thoracic cavity, obviating the need for incisionselsewhere in the body. For these reasons, the use of an IMA graft willbe described here, although the techniques described are equallyapplicable to vein grafts, prosthetic grafts, and other types of grafts.

The IMA must be dissected from its native location in the anterior wallof the thoracic cavity. To accomplish this, a cutting instrument such asan electrocautery tool (not shown), a surgical knife (not shown) orscissors 190, along with grasping forceps 192, are introduced throughtrocar sleeves 180. The grasping forceps shown in FIG. 7A are usuallypreferred for this purpose. These instruments may be introduced atvarious locations, but are usually inserted through trocar sleeves inthe right lateral side of the chest to allow the instruments to reachthe anterior wall of the thoracic cavity. Using these instruments, asection of the IMA, usually about 10 to 20 cm in length, is cut awayfrom the surrounding tissue with the vessel still intact. Branches ofthe IMA which are too large to cauterize may be double clipped withsmall clips and divided between the clips. A clip applier like thatillustrated in FIGS. 11-12 may be used for this purpose. A section ofthe IMA is chosen which, when cut distally, will reach the desiredanastomosis site on the LAD. This mobilized section of the IMA must thenbe isolated to stop blood flow through it. Such isolation may beaccomplished by introducing a removable clamp (not shown) into thethoracic cavity and applying the clamp to the IMA near the distal end ofthe mobilized section but proximal to the point at which the vessel isto be transected. A conventional clamp such as a Fogarty clamp availablefrom Baxter Healthcare Corp. of McGaw Park, Ill. may be used for thispurpose. A clip applier, such as that illustrated in FIGS. 11-12, isthen introduced into the thoracic cavity and one or more surgical clipsare applied to the IMA distal to the point at which it is to betransected. A scissors 190 or other cutting instrument is then used totransect the IMA near the distal end of the mobilized section betweenthe removable clamp and the surgical clips.

The distal end of the mobilized IMA is then prepared for anastomosis.Usually, forceps 192 arc used to withdraw the mobilized section from thethoracic cavity through one of trocar sleeves 180. The distal end isthen prepared for anastomosis by cutting away a distal portion of thepedicle surrounding the vessel so that a distal segment of the vessel isexposed. The distal end of the vessel is transected at anon-perpendicular angle suitable for attachment to the LAD in afishmouth configuration. The vessel may then be returned to the thoraciccavity.

The patient must then be placed on cardiopulmonary bypass, and the heartmust be stopped. If the operation is to be performed usingminimally-invasive techniques, these must be accomplished without makinga sternotomy or other gross thoracotomy in the patient's chest.Minimally-invasive techniques for establishing cardiopulmonary bypassand arresting the health without opening the patient's chest aredescribed in copending application Ser. No. 08/023,778, which has beenincorporated herein by reference, as well as in copending applicationsSer. No. 07/991,188, filed Dec. 15, 1992, and Ser. No. 8/123,411, filedSep. 17, 1993, which are both hereby incorporated herein by reference intheir entirety.

Once the heart has been stopped and the patient is supported oncardiopulmonary bypass, the anastomosis of the IMA to the LAD may beperformed. As illustrated in FIG. 14, an opening O is formed in the LADat the desired location of the anastomosis, distal to the lesion whichis to be bypassed. A scissors 190 or other cutting instrument isintroduced through a trocar sleeve 180 and a small incision is formed inthe LAD, usually about 2 to 5 mm in length. The rearward cuttingscissors illustrated in FIG. 9 may also be useful for this purpose,depending upon the orientation of the heart and/or LAD relative to theuser and relative to the trocar sleeve through which the instrument isintroduced.

It may be necessary, either before or after an opening is formed in theLAD, to dissect a small section of the LAD on either side of theanastomosis site away from the epicardium to obtain better access forperforming an anastomosis. Scissors 190 or other cutting instruments maybe used for this purpose. The dissected section of the LAD may beretracted away from the surface of the heart using conventional meanssuch as Retract-O-Tape Vascular Loops available from Quest Medical ofDallas, Tex.

To perform the anastomosis, the IMA is sutured to the LAD over openingO. As illustrated in FIG. 15, a grasping instrument such as forceps 192is introduced through a trocar sleeve for holding the IMA in positionduring the anastomosis. One or more needle drivers 194 are alsointroduced into the thoracic cavity, as well as a suture 196, usuallyhaving needles 198 on both ends. Needle drivers 194 are used tomanipulate needles 198 so as to suture the distal end of the IMA to theLAD, under visualization by means of endoscope 182 (FIG. 13) or othervisualization device.

Various techniques may be used for suturing the IMA to the LAD. Anexemplary technique is illustrated in FIGS. 16A-16E and is describedcomprehensively in Kirklin and Barratt-Boyes, Cardiac Surgery, pp.207-277(1986), the disclosure of which is incorporated herein byreference. At least one pair of needle drivers 194 are required, alongwith a grasping instrument such as forceps 192. It may be seen from theillustrations that the suture is passed sequentially through the wall ofthe LAD around the edges of opening O and through the wall of the IMAaround its distal end 200. This is repeated until suture loops have beenmade about the entire circumference of the IMA spaced approximately 0.3mm apart The loops are drawn tight and the suture is tied off in aconventional manner to provide a secure and fluidly sealed attachment ofthe IMA to the LAD, as illustrated in FIG. 17. The removable clip(described above) is then removed from the IMA, allowing blood to flowthrough the IMA and into the LAD after the heart has been restarted.

When the anastomosis has been completed, the patients heart is restartedand cardiopulmonary bypass is discontinued. All trocar sleeves andcannulas are removed from the patient, and the thoracic incisions andarterial and venous punctures are closed. The patient is then recoveredfrom anesthesia.

The microsurgical instruments of the invention are specially adapted tofacilitate the ultra-precise microsurgical steps of thoracoscopic CABG.The IMA, LAD, and other body structures manipulated during the CABGprocedure are extremely small, with diameters in the range of 1 to 4 mm,and are relatively fragile structures which must be handled gently andprecisely. The microsurgical forceps, scissors, needle drivers, and clipappliers of the invention are well-suited to grasping these structures,making the necessary transections, incisions, and ligations, andapplying extremely small sutures, allowing anastomoses to be performedaccurately, efficiently, repeatably, and with minimal trauma. Theinstruments of the invention not only have the very small dimensionsnecessary for such microsurgery, but the means of holding and actuatingthese instruments allow extremely precise actuation and control of theend-effectors. Moreover, the elongated, low-profile configuration, highstiffness, and optimal end-effector geometries of these instrumentsfacilitate the performance of CABG and other operations through smallincisions or trocar sleeves rather than through the gross, openthoracotomies used in conventional open-heart surgery.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention, which is defined by appendedclaims.

What is claimed is:
 1. A surgical instrument comprising:an outer shaft;an inner shaft generally parallel to the outer shaft and movablerelative thereto; an actuator body attached to a first shaft selectedfrom the outer shaft and the inner shaft; a first arm linked to a secondshaft selected from the outer shaft and the inner shaft and having aproximal end and a distal end, the proximal end being pivotally coupledto the actuator body and the distal end extending distally and outwardlyfrom the actuator body on a first lateral side of the outer shaft toform an acute angle therewith; a second arm linked to the second shaftand having a proximal end and a distal end, the proximal end beingpivotally coupled to the actuator body, and the distal end extendingdistally and outwardly from the actuator body on a second lateral sideof the outer shaft opposite the first lateral side to form an acuteangle therewith, the distal ends of the first and second arms beingpivotable between an open position away from each other and a closedposition closer to each other so as to move the inner shaft relative tothe outer shaft; and a locking mechanism coupled to the first arm andconfigured to engage the second arm in the closed position to retain thefirst and second arms in the closed position.
 2. The surgical instrumentof claim 1 wherein the locking mechanism comprises a beam having a firstend attached to the first arm and a second end extending inwardly towardthe second arm, the second end being deflectable and having a catchthereon for engaging the second arm in the closed position.
 3. Thesurgical instrument of claim 2 further comprising a step mounted to thesecond arm for engaging the catch in the closed position.
 4. Thesurgical instrument of claim 2 wherein the catch is configured torelease the second arm upon pushing the first arm toward the second armfrom the closed position.
 5. The surgical instrument of claim 4 whereinthe catch is in a detected configuration when engaging the step in theclosed position.
 6. The surgical instrument of claim 5 wherein the catchis configured to recoil to an unbiased configuration upon pushing thefirst arm toward the second arm from the closed position, the catchbeing configured to avoid engagement with the step in the unbiasedconfiguration as the first and second arms return to the open position.7. The surgical instrument of claim 1 wherein the locking mechanismcomprises a ratchet for releasably locking the first arm relative to thesecond arm in a plurality of positions between the open and closedpositions.
 8. The surgical instrument of claim 7 wherein the ratchetcomprises a rocker arm coupled to the first arm and having a pluralityof teeth along an edge thereof, and a pawl on the second arm forsequentially engaging the teeth as the first arm is moved toward thesecond arm.
 9. The surgical instrument of claim 7 wherein the rocker armis pivotably mounted to the first arm and biased in a first directionsuch that the teeth are urged against the pawl.
 10. The surgicalinstrument of claim 1 further comprising an end-effector coupled to theouter shaft and coupled to the inner shaft so as to move in response tomovement of the inner shaft relative to the outer shaft.
 11. Thesurgical instrument of claim 10 wherein the end effector comprises afirst jaw coupled to the outer shaft and a second jaw coupled to theinner shaft, the second jaw being movable relative to the first jaw. 12.The surgical instrument of claim 11 wherein the second jaw is pivotablycoupled to the first jaw.
 13. The surgical instrument of claim 12wherein the first and second jaws have opposing faces for clamping anobject therebetween upon closure of the jaws.
 14. The surgicalinstrument of claim 12 wherein the first and second jaws have cuttingedges movable in a shearing relationship as the jaws are closed.
 15. Thesurgical instrument of claim 1 further comprising a spring for biasingthe first and second arms into the open position.
 16. A surgicalinstrument comprising:an outer shaft; an inner shaft generally parallelto the outer sly and movable relative thereto; an actuator body attachedto a first shaft selected from the outer shaft and the inner shaft; afirst arm linked to a second shaft selected from the outer shaft and theinner shaft and having a proximal end and a distal end, the proximal endbeing pivotally coupled to the actuator body and the distal endextending distally and outwardly from the actuator body on a firstlateral side of the outer shaft to form an acute angle therewith; asecond arm linked to the second shaft and having a proximal end and adistal end, the proximal end being pivotally coupled to the actuatorbody, and the distal end extending distally and outwardly from theactuator body on a second lateral side of the outer shaft opposite thefirst lateral side to form an acute angle therewith, the distal ends ofthe first and second arms being pivotable between an open position awayfrom each other and a closed position closer to each other so as to movethe inner shaft relative to the outer shaft; and a flat spring having afirst end engaging an inner surface of the first arm and a second endengaging an inner surface of the second arm for biasing the first andsecond arms into the open position.
 17. The surgical instrument of claim16 wherein the flat spring is generally U-shaped when engaging the firstand second arms and is biased toward a flat configuration.
 18. Thesurgical instrument of claim 17 wherein the flat spring has a first endsegment disposed along an inner surface of the first and second endsegment disposed along an inner surface of the second arm, and aconnecting segment between the first and second end segments, theconnecting segment being disposed between the proximal ends of the firstand second arms.
 19. A surgical instrument comprising:an outer shaft; aninner shaft generally parallel to the outer shaft and movable relativethereto; an actuator body attached to a first shaft selected from theouter shaft and the inner shaft, the actuator body having a longitudinalchannel therein; a clevis slidably positioned in the longitudinalchannel and attached to a second shaft selected from the outer shaft andthe inner shaft; a first arm linked to the clevis and having proximaland distal ends, the proximal end being pivotally coupled to theactuator body and the distal end extending distally and outwardly fromthe actuator body on a first lateral side of the outer shaft to form anacute angle therewith;a second arm linked to the clevis and havingproximal and distal ends, the proximal end being pivotally coupled tothe actuator body, and the distal end extending distally and outwardlyfrom the actuator body on a second lateral side of the outer shaftopposite the first lateral side to form an acute angle therewith, thedistal ends of the first and second arms being pivotable between an openposition away from each other and a closed position closer to each otherso as to slide the clevis within the longitudinal channel, therebymoving the inner shaft relative to the outer shaft.
 20. The surgicalinstrument of claim 19 wherein the first arm is linked to the clevis bya first link having a first end pivotably coupled to the first arm and asecond end pivotably coupled to the clevis and wherein the second arm islinked to the clevis by a second link having a first end pivotablycoupled to the second arm and a second end pivotably coupled to theclevis.